Grease compositions have been known for a long time. Classically, greases have contained an oil of lubricating viscosity and a thickening agent. Thickening agents have often been soaps, such as the metallic salts of fatty acids. Calcium soaps, as grease-thickening agents, have a long history. More recently, complex greases have been developed which use a combination of a salt of a long chain acid, such as stearic acid, and a salt of a short chain acid, such as acetic acid to form a thickening metallic salt soap. Calcium is typical metallic counter ion for this type of grease. Sodium, lithium, and aluminum have been used to form soaps, which act as grease thickeners. Organophilic bentonite clays have been used as grease thickeners. More recently, ureas have been used as grease thickeners. The ureas are prepared by reacting an isocyanate with an amine. Monoureas may be prepared by reacting a monoisocyanate with a monoamine. Polyureas are prepared by reacting combinations of diamines, monoamines, diisocyanates, and monoisocyanates. A common reaction mixture includes a diisocyanate, a diamine and a monoamine. The monoamine is included in the reaction mixture since it acts to terminate the polymer chain and prevents it from becoming too long. The basic reaction is illustrated by the following equation: EQU 2MA+2DI+DA.fwdarw.MA-DI-DA-DI-MA Tetraurea
MA=Monoamine PA1 DI=Diisocyanate PA1 DA=Diamine. PA1 (1) hydrocarbyl groups, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl), aromatic, aliphatic- and alicyclic-substituted aromatic groups and the like as well as cyclic groups wherein the ring is completed through another portion of the molecule (that is, any two indicated groups may together form an alicyclic group); PA1 (2) substituted hydrocarbyl groups, that is, those groups containing non-hydrocarbon groups that, in the context of this invention, do not alter the predominantly hydrocarbyl nature of the hydrocarbyl group; those skilled in the art will be aware of such groups, examples of which include ether, oxo, halo (e.g., chloro and fluoro), alkoxyl, mercapto, alkylmercapto, nitro, nitroso, sulfoxy, etc.; PA1 (3) hetero groups, that is, groups that, while having predominantly hydrocarbyl character within the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Suitable heteroatomns will be apparent to those of skill in the art and include, for example, sulfur, oxygen, nitrogen and such substituents as pyridyl, furanyl, thiophenyl, imidazolyl, etc. PA1 R.sub.1 and R.sub.2 are the same or different type of hydrocarbylenes having from 1 to 30 carbons and preferably from 2 to 10 carbons and more preferably from 2 to 4 carbons; PA1 R.sub.0 is selected from hydrogen or a C.sub.1 -C.sub.4 alkyl and preferably hydrogen; PA1 x is an integer from 0 to 4; PA1 y is 0 or 1; and PA1 z is an integer equal to 0 when y is 1 and equal to 1 when y is 0. PA1 n is an integer from 0 to 4; PA1 R.sub.3 is the same or different hydrocarbyl having from 1 to 30 carbon atoms, preferably from 10 to 24 carbons; PA1 R.sub.4 is the same or different hydrocarbylene having from 2 to 30 carbon atoms, preferably from 6 to 15 carbons; and PA1 R.sub.5 is the same or different hydrocarbylene having from 1 to 30 carbon atoms, preferably from 2 to 10 carbons. PA1 n.sup.1 is an integer of 0 to 8, R.sub.4 is the same or different hydrocarbylene having from 2 to 30 carbon atoms, preferably from 6 to 15 carbons; X and Y are monovalent radicals selected from TABLE I below. PA1 (a) a reactant of the formula EQU R.sub.m --Ar--OH PA1 (b) glyoxylic acid shown below as the hydrate ##STR16##
Additives are frequently added to grease to improve various performance properties. Among the properties which may be improved through the use of additives are oxidation stability, water resistance, rust protection, corrosion protection, antiwear, extreme pressure, adhesiveness, color, oil separation, low temperature flow, and high temperature performance. Salicylates have been used in grease compositions, some times as part of a complex grease, and some times as additives.
Chinese Patents 1052890 and 1052891, as abstracted in the Derwent Database under the numbers WPI ACC NO 92-124047/16 and 92-124048/16, disclose lubricating greases containing a thickening agent which includes lithium 12-hydroxy-stearate and lithium salicylate. The salicylate appears to be an unsubstituted salicylate and is said to be part of the thickening agent.
U.S. Pat. No. 3,660,288 discloses a polyurea grease containing the magnesium salts of unsaturated fatty acids. The alkali metal, other alkaline earth metal and zinc salts of an unsaturated fatty acid were tested in the composition, but did not impart the desired rust resistance.
U.S. Pat. No. 3,711,407 discloses a grease composition containing an alkali metal salt of hydroxybenzoic acid. The salt is oil insoluble and forms in small particles evenly distributed throughout the composition.
U.S. Pat. No. 3,846,314 discloses a polyurea grease composition containing an alkaline earth aliphatic carboxylate, especially calcium acetate.
U.S. Pat. No. 3,846,315 discloses polyurea greases containing alkaline earth metal 1-3 carbon monocarboxylates.
U.S. Pat. No. 3,868,329 discloses a polyurea grease composition containing an alkaline earth metal aliphatic monocarboxylate containing from 1 to 3 carbon atoms. Calcium acetate is preferred. The composition also includes a Mannich base.
U.S. Pat. No. 3,983,041 discloses a polyurea grease, which contains an alkaline earth carbonate or an alkaline earth lower carboxylate. The alkaline earth salts serve as rust inhibitors.
U.S. Pat. No. 4,246,605 discloses a polyurea grease containing antimony dipentyldithiocarbamate. The antimony salt provides extreme pressure and antiwear properties to the grease.
U.S. Pat. No. 4,719,023 discloses a grease composition that comprises a base fluid, a thickener, a calcium salicylate and a magnesium salicylate. The salicylates may be neutral but are preferably overbased alkyl salicylates. The calcium salicylate improves anti-rust properties, and the magnesium salicylate counteracts the decrease in dropping point caused by the addition of the calcium salicylate. The thickener may be a substituted urea; however, the preferred thickening agent is an alkali fatty acid soap.
U.S. Pat. No. 4,828,733 discloses greases containing the cuprous salt of 4-hydroxybenzoic acid (salicylic acid is 2-hydroxybenzoic acid). The salts are primarily antioxidants. However, friction-reducing and wear protection are also disclosed.
U.S. Pat. No. 4,929,369 discloses a grease that may be thickened with polyurea and that includes a monovalent salt of a carboxylic acid in which the --COOH group is attached to a ring atom of a fused ring system.
U.S. Pat. No. 5,011,617 discloses a polyurea-thickened grease and an alkaline earth salt of a 1-3 carbon aliphatic monocarboxylate.
U.S. Pat. No. 5,084,193 discloses a polyurea grease that contains, in addition, a simple or complex calcium soap as a further thickener.
U.S. Pat. No. 5,207,935 discloses a polyurea grease containing a calcium, barium, magnesium or zinc salt of an alkylsuccinic acid, such as dodecenylsuccinic acid in combination with a sulfonate. The succinic salt acts as a rust inhibitor and texture improver.
Japanese Patent 3035091 discloses greases thickened with lithium and sodium soaps which include a wide variety of anti-static agents including magnesium oleate, copper oleate and chromium alkylsalicylate.
Japanese Patent 57212297 discloses a lithium grease that includes alkaline earth salicylates.
British Patent 2,215,346 discloses grease compositions thickened with lithium soap, lithium borate, lithium hydroxy-benzoate and a polyol. The lithium hydroxy-benzoate is either the lithium salt of a hydroxy-benzoic acid or the lithium salt of a low alcohol ester of such an acid.
EP Patent 84,910 discloses a lithium complex grease composition that includes lithium salicylate as a complexing agent.
EP Patent 151,825 discloses a continuous process for manufacturing lubricating greases in which the thickener is a soap and various complexing agents, such as acetic and salicylic acid, may be added.
EP Patent 566,326 discloses a polyurea grease with molybdenum dialkyldithiophosphates and ashless dithiophosphates as additives.
Soviet Patent SU 924089 discloses a grease containing a high ash calcium alkylsalicylate. The calcium alkylsalicylate prevents stratification.
U.S. Pat. No. 2,933,520 to Bader relates to compounds represented by the formula: ##STR1##
in which R.sub.1 may be hydrocarbon, halogen, such as chlorine or the like, and R.sub.2 is hydrocarbon, e.g., alkylene, other than methylene, containing at least two carbon atoms such as ethyl, propyl, butyl, with either normal, or branched chains and containing, for example, up to 10, 12 or even more carbon atoms. The Ar groups are aromatic rings. They may be unsubstituted, but one or both thereof can contain substitutents such as alkyl (methyl, ethyl, propyl, butyl, isopropyl, isobutyl), halogen, (chlorine, bromine), nitro, sulfo and others. The nature of each of these groups affecting properties such as boiling point, solubility, toxicity, and bactericidal, fungicidal, insecticidal and like properties.
U.S. Pat. No. 3,133,944 to Christensen teaches heavy metal salts represented by: ##STR2##
wherein the R.sub.1 is an alkyl of 1-4 carbons, R.sub.2 is an alkylene of 2-6 carbons and Ar is an aromatic group that may be substituted with one or more methyl groups and others. The salts are said to be adapted to retard or prevent the growth of biological organisms, particularly molds and mildews.
U.S. Pat. No. 5,356,546 relates to metal salts of the general formula:
A.sup.y- M.sup.y+ (I)
wherein M represents one or more metal ions, y is the total valence of all M, and A presents one or more anion containing groups having a total of about y individual anionic moieties and each anion containing group is a group of the formula: ##STR3##
wherein T is an organic group acted from a group of structures, t is 0 or 1, R is an alkyl, alkenyl or aryl group containing at least 8 carbon atoms, R.sub.1, R.sub.2, and R.sub.3 are independently H or a hydrocarbyl group, m is an integer from 1 to 10, c is an integer such that the sum of m, c and t does not exceed the valence capacity of Ar, and Z is OH, OR.sub.4 or O.sup.-. The salts find utility in lubricants and fuels compositions.